Thermosettable modified phenolic polyester imide resins

ABSTRACT

Modified phenolic resins and cured resins prepared therefrom.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates, to certain novel modified phenolic imide resins.More particularly, this invention relates to such resins which haveimproved properties.

2. Prior Art

Phenolic resins are a class of synthetic materials that have growncontinuously in terms of volume and applications for over severaldecades. The building blocks used in greatest volume are phenol andformaldehyde. Other important phenolic starting materials are thealkyl-substituted phenols, including cresols, xylenols,p-tert-butyl-phenol,p-phenylphenol, and nonylphenol. Diphenols, eg,resorcinol (1,3-benzenediol) and bisphenol-A [bis-A or2,2-bis(4-hydroxylphenyl)propane], are employed in smaller quantitiesfor applications requiring special properties. In addition toformaldehyde, acetaldehyde or furfuraldehyde sometimes are employed butin much smaller quantities. The greater latitude in molecular structure,which is provided by varying the raw materials, chemistry, andmanufacturing process, has made possible an extremely large number ofapplications for these products as a results of the array of physicalpropeties that arise from the synthetic options.

The early investigation of the reaction of phenol and formaldehyde beganwith the work of von Baeyer and others in the early 1870s as anextension of phenolbased dye chemistry. The initial experiments resultedin soluble, amorphous products whose properties elicited littleinterest. Insoluble, cross-linked products were reported in the late1880s, but these products also were not perceived us useful materials.In 1899, the first patent for a phenolic-resin product intended for useas a hard-rubber substitute was granted. The first commercial productwas introduced as a shellac substitute by the Louis Bluner Company inthe early 1900's. Process patents were issued in 1894 and 1895 forortho- and para-methylolphenol, respectively.

Key innovations in early phenolic-resin manufacture included control ofthe molecular structure and the use of heat and pressure to achievedesirable physical properties in filled compositions. Studies in the useof acidic or basic catalysts and of changes in the molar ratio offormaldehyde to phenol resulted in the definition of two classes ofpolymeric materials which are referred to as Bakelite resins.Caustic-catalyzed products, which are prepared with greater than a 1:1mol ratio of formaldehyde to phenol, can be used to form cross-linked,insoluble, and infusible compositions in a controlled fashion. With lessthan a 1:1 mol ratio of formaldehyde to phenol, the resultant productsremain soluble; furthermore, acid catalysis yields permanently stablecompositions, whereas base-catalyzed materials can be advanced inmolecular weight and viscosity. Possibly of greatest importance to earlycommercialization, however, was the reduction to practice of the use ofheat and pressure to produce essentially void-free molding compositions.

Resole resins are made with an alkaline catalyst and a molar excess offormaldehyde. Novolak or novolac resins are prepared with an acidcatalyst and less than one mole of formaldehyde per mole of phenol. Theinitial reaction involved in the preparation of resolated novolaks iscarried out with an acid catalyst and less than a 1:1 mol ratio offormaldehyde to phenol. After formation of the novolak, the pH isadjusted so that the reacttion mixture is basic and additionalformaldehyde is added. Resoles and resolated novolaks are inherentlythermosetting and require no curing agent for advancement. Novolaks, bycomparison, are thermoplastic and require the addition of a curingagent, the most common being either hexamethylenetetramine or a resole.The stages of molecular weight advancement are characterized by liquidor solid phenolic polymer which is soluble in certain organic solventsand is fusible; a solid resin which is insoluble but swelled by organicsolvents and, although softened by heat, exhibits essentially no flow;and an insoluble, infusible product which is not swelled by solvents norsoftened by heat, ie, the system is in a highly cross-linked state.

Phenolic resins have many uses. For example, such materials are used asbonding agents in friction materials such as brake linings, clutchfacings, transmission bonds and the like. For example U.S. Pat. Nos.4,096,108; 4,268,657; 4,218,361;, 4,219,452; and 3,966,670 describevarious friction materials in which a phenolic resin is employed as thebonding agent. Phenolics are also used as molding materials, and ascoatings and adhesives. Phenolics resins developed for non-flammabilityand long term temperature stability to 230° C. have been studied incarbon-fiber composities. Potential for such composities lies inadvanced aircraft application.

While present day phenolics exhibit several beneficial properties theysuffer from a number of disadvantages which restrict their utility. Forexample, such materials exhibit less than desirable thermal oxidativestability. Other major problems of present day phenolic technologyinclude a need for auxilary chemicals such as hexamethylene tetraamineto crosslink the phenolic which often results in the production ofvolatile by-products such as ammonia during crosslinking. Still otherproblems result from the fact that crosslinking is often extensive andis not controllable.

Various modifications to phenolics have been proposed to obviate certainof the disadvantages attendant to these resins. For example,epichlorohydrin has been reacted with the hydroxyl groups of novalakforming epoxy novalak. Moreover, n-chloro-2-propene has been reactedwith the hydroxyl groups of novalak to form the corresponding formmethylon resin. Similarly, Japanese patent publication Nos. 59-149918and 58-34822 describe a method of preparing a phenolic resin containingcyanate groups. In this method, a trialkyl ammonium salt of a phenolnovolak is reacted with excess cyanhalogenide in an organic solvent.

Polyesterimides are known polymeric composition compounds. For example,polyesterimides and processes for their preparation are described inGreat Britain Pat. Nos. 973,377; 1,070,364; 1,026,032; and 1,095,663;U.S. Pat. No. 3,839,264; D.F. Loncrini et al., J. Polym. Sci, Vol. 4, p.440 (1966), and S. Das et al., J. Appl. Polym. Sci., Vol. 26, p. 957(1980).

Crosslinked polymers, for example, polycyanates (crosslinked polymers)derived by the polycyclotrimerization of aromatic cyanates are known.See for example, U.S. Pat. No. 4,026,913, which describes cyanic acidesters of aromatic polycarbonates which can be cured to producecrosslinked polycyanurates. Also see the references, Kunst-stoffe, Bd.58, pp. 827-832 (1968) by R. Kubens et al., and Dokl Akad. Nauk SSSR,Vol. 202, pp. 347-350 (1972) by V. V. Korsak et al., which describe thecyclotrimerization of aryl cuanurates and properties of crosslinkedpolymers derived therefrom. In addition, the references, U.S. Pat. No.4,040,796 (1977) and German Offenlegungschrifte Nos. 2,549,529;2,546,290; and 2,541,315 describe processes for producing certain polyfunctional cyanic acid esters, and cured products derived therefrom.

U.S. Pat. No. 4,157,360 describes cured compositions consistingessentially of a cross-linked cyanurate polymer and a thermoplasticpolymer of at least film forming molecular weight. This compositionpossesses a Vical softening temperature of at least about 10° C. abovethat of the thermoplastic polymer alone as determined by ASTM 1525; andan elongation-to-break value which is at least twice as great as that ofthe crosslinked polymer alone or determined by ASTM D-638 at roomtemperature.

SUMMARY OF THE INVENTION

One aspect of the present invention is directed to a modified phenolicresin of Formula I: ##STR1## wherein: A and B are the same or differentand are moieties of the formula: ##STR2## n is a positive whole numbergreater than or equal to 1; q and r are the same or different at eachoccurrence and are whole numbers from 0 to 3, with the proviso that thesum of q and r at each occurrence is equal to 3;

o and p are the same or different at each occurrence and are wholenumbers from 0 to 4, with the proviso that the sum of o and p at eachoccurrence is is equal to 4;

--X-- is a divalent organic radical; and

R₃ is the same or different at each occurrence and is a substituentother than hydrogen which is unreactive under conditions necessary tocrosslink the cyanurate moieties.

Yet another aspect of this invention relates to a new phenolic resin ofthe Formula II: ##STR3## wherein R₃, q, r, o, p, and X are as describedabove, k is a positive whole number, Y is hydrogen, or hydrogen and--CN--, --R-- is a divalent organic moiety, and --Z₁ -- and --Z₂ -- arethe same or different and are of the formula: ##STR4##

Another aspect of this invention relates to precured compositionscontaining the above-referenced modified phenolic resins of Formula Iand Formula II, and to partially cured, completely cured andincompletely cured compositions of Formulas II formed by the curing orcrosslinking of the modified phenolic resin of this invention to varyingdegrees. As used herein, "completely cured" modified phenolic resins arethose in which less than about 20 mole percent of the originalcrosslinkable groups, i.e., hydroxyl or cyano, remain unreacted asdetermined by the method of infrared spectrophotometry; "precured"modified phenolic resins are those in which substantially about 100 molepercent of the original crosslinkable groups, i.e., hydroxyl or cyano,are unreacted as determined by the method of infrared spectrophotometry;"partially cured" modified phenolic resins are those in which from about40 to about 70 mole percent of the original crosslinkable groups, i.e.,hydroxyl or cyano are unreacted as determined by infraredspectrophotometry; and "incompletely cured" modified phenolic resins arethose in which from about 40 to about 20 mole percent of the originalcrosslinkable groups, i.e., hydroxyl or cyano are unreacted asdetermined by infrared spectrophotometry. Still, another aspect of thisinvention related to such compositions comprising said phenolic resin inadmixture with one or more other materials as for example, thermosettingand thermoplasic polymers such as kevlar and polyethylene, fillers asfor example boron, carbon, and the like.

Certain crosslinked or cured phenolic resins of this invention areformed by crosslinking the resin of Formula II wherein Y is hydrogen bytreatment with a conventional phenolic crosslinking agent such ashexamethylene tetramine, resole and paraformaldehyde to provide thedesired degree of curing or crosslinking. Another crosslinked or curedphenolic resin of this invention is prepared by crosslinking phenolicresin of Formula II wherein Y is a mixture of --CN and hydrogen by"polycyclotrimerization".

The cured resin derived from modified phenolic resin of this invention,and the modified phenolic resin of this invention exhibit severaladvantages over conventional phenolic resins. For example, certain ofthese materials are self crosslinking, and thus do not requireauxilliary chemicals for crosslinking. Moreover, the cross-linkedmaterial has greater oxidative, mechanical and thermal stability ascompared to conventional phenolic resins, and no volatile, potentiallyenvironmentally hazardous by-products are produced during crosslinking.Furthermore, the claimed crosslinked phenolic resins have higher charforming properties than the conventional phenolics and polyesterimideresins.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

One aspect of this invention relates to a phenolic esterimide resin ofthe Formula II wherein R₃, r, n, --X--, o, p, k, --Z₁ --, --Z₂ --, Y and--R-- are as described above. In Formula II, --R-- is a divalent organicradical. Illustrative of useful --R-- groups are alkylene as forexample, methylene, 3-methoxyhexamethylene, 3-methylhexamethylene,3-methylhepta-methylene, 1,2-ethylene, 1,3-propylene, 1,10-decalene,1,4-butylene, 1,7-heptalene, 2,2-dimethyl-1,3-propylene, 1,6-hexylene;1,8-octalene and the like; arylene such as 1,3-phenylene, 1,4-phenylene,biphenylene, 1,3-benzenedimethylene, 1,4-benzenedimethylene,2,2-bis-(4-phenylene)propane, 1,5-naphthalene, bis-(4-phenylene)methane,4,4'-phenylene propane, 4,4-diphenylenedimethane and the like; andcycloalkylene such as cyclohexylene, cyclooctylene,1,3-cyclohexanedimethylene, 1,4-cyclohexanedimethylene; and the like.Also illustrative of useful --R-- groups are arylene, alkylene orcycloalkylene which may include one or more divalent oxygen, nitrogen,sulfur, sulfenyl, keto, sulfonic ester, and ester moieties as forexample oxybisethylene, oxybispropylene, ethylenedioxylbisethylene,oxybisphenylene, 2,2'-diethylene sulfone, 2,2'-diethylene sulfide,3,3'-dipropylene sulfone, 3,3'-dipropylene ether, oxybisnaphthalene,oxybiscyclohexylene, thiobisethylene, thiobisphenylene,aminobisphenylene, ammobisethylene, thiobiscyclohexylene,sulfonylbisethylene, sulfonylbisphenylene, 4,4'-phenylene ethane,3,4'-phenylene propane, 4,4'-phenylene ether, 4,4'-phenylene sulfone,4,4'-phenylene sulfide, sulfonylbiscyclohexylene, sulfinylbisphenylene,sulfinylbisethylene, and the like. Exemplary of useful --R-- groups arealkylene terminated polydiorganosiloxanes such as bis-(3-propylene)tetramethyl disiloxane, bis-(4-butylene)tetra methyl disiloxanes and thelike.

R₃ is an inert substituent. Illustrative of suitable --X-- groups aresuch inert substituents as halogen, trihalomethyl, alkyl, alkoxyl,phenyl, and the like.

--X-- is a divalent organic radical. Illustrative of suitable R₃ groupsare alkylene such as methylene, ethylmethylene, difluoromethylene,2-ethypentylmethylene, methylmethylene, isopropymethylene,isobutylmethylene, pentylmethylene, furylmethylene, and the like;arylene such as 1,3-benzenediamethylene, phenylmethylene,1,4-benzenedimethylene, 2,2-bis-(4-phenylene)propane,4-methoxyphenylmethylene, bis-(4-phenylene)methane, 4,4-diphenylenesdimethylethane and the like; and cycloalkylene such as cycloheylene,cyclooctylene, 1,3-cyclohexandimethylene, and the like;

In the preferred embodiments of the invention:

--R-- is a divalent organic radical selected from the group consistingof divalent aromatic radicals having from 6 to about 20 carbon atoms,alkylene having from 1 to about 20 carbon atoms, cycloalkylene havingfrom 3 to about 20 carbon atoms, polydiorganosiloxanes terminated withalkylene having from about 2 to about 8 carbon atoms, and divalentradicals of the formula: ##STR5## wherein Q is selected from the groupconsisting of: ##STR6## where y is from 1 to about 20. q and r are thesame or different and are positive whole numbers from 0 to 3, with theproviso that the sum of q and r at each occurrence is 3;

Y is hydrogen, or hydrogen and --CN with the proviso that when Y ishydrogen and --CN is from about 5 to about 80 mole percent of Y is --CN;

o and p are the same or different and are positive whole numbers from 0to 4, with the proviso that the sum of o and p at each occurrence is 4;

--X-- is substituted or unsubstituted methylene or 1,4-phenyldimethylenewherein permissible substituents are alkyl, halogen or furyl;

k is is a positive whole number from 1 to about 25;

R₃ is alkyl; and

n is a positive number from 1 to about 10.

Amongst the preferred embodiments most preferred are those embodimentsof the above formula in which:

0 is 0 or 1;

pis 3 to 4;

--X-- is methylene, methylene substitued with alkyl having from about 1to about 10 carbon atoms, halogen, furfuryl and xylene;

R₃ is methyl or ethyl;

n is 1 to about 6;

k is 1 to about 15;

Y is hydrogen, or hydrogen and --CN with the proviso that when Y ishydrogen and --CN from about 15 to about 75 mole percent of Y is --CN;

--R-- is a divalent radical selected from the group consisting ofdivalent aromatic radical and divalent radicals of the formula: ##STR7##r is o or 1; and q is 2 to 3.

Amongst these particularly preferred embodiments, most preferred arethose embodiments wherein:

k is 1 to about 5;

n is 1 to about 4;

p is 4

o is 0;

Y is hydrogen, or hydrogen and --CN with the proviso that when y ishydrogen and --CN from about 25 to about 50 mole percent of Y is --CN;

r is 0;

--R-- is selected from the group consisting of phenylene, diphenylene,naphthalene and divalent radicals of the formula: ##STR8## where Q isselected from the group consisting of ##STR9## where y is from 1 toabout 10;

--X-- is a moiety of the formula: ##STR10## q is 3.

The phenolic resin of Formula II in which Y is hydrogen and --CN isprepared by treating the phenolic imide resin of Formula II in which Yis hydrogen with a cyanurating agent such as a cyanogen halide,preferably cyanogen chloride or cyanogen bromide until the desiredamount of cyannate groups are formed, generally at least about 10 mole %of the Y groups. In the preferred embodiments of the inventionsufficient cyanurating agent is used such that from about 5 to about 80mole percent of y groups are --CN and in the particularly preferredembodiments, from about 15 to about 75 mole percent of the y groups are--CN. Amongst these particular preferred embodiments most preferred arethose embodiments in which sufficient cyanurating agent is used suchthat from about 25 to about 50 mole percent of the Y groups are --CN.Methods of forming cyanurate groups are well known in the art and willnot be described herein in any great detail. Briefly stated in this is anucleophilic displacement reaction in which a cyanogen halide,preferably chloride or cyanogen bromide is reacted with the phenolate ofthe resin of Formula II wherein the required percentage of Y hydrogengroups have been displaced by an acid acceptor solvent. The phenolate isformed by reacting the resin of Formula II wherein Y is hydrogen with anacid acceptor solvent as for example, a tertiary amine such astriethylamine, in an amount sufficient to displace the desired quantityof Y hydrogen groups. Reaction parameters can vary widely. The reactionis usually carried out over a period of from about 4 to about 6 hours atatmospheric pressure and at a temperature of from about 0° C. to about120° C. in an aprotic solvent, such as N-methyl pyrrolidone, dimethylsulfoxide and N,N-dimethyl formamide.

The phenolic imide of Formula II in which Y is hydrogen is prepared byreacting the phenolic anhydride of this invention depicted in Formula Iwith a diamine of the formula:

H₂ N-R-NH₂

where o, p, k, n, --X--, R₃, q, r, and --R-- are as described above,followed by imidization of the reaction mixture. This reaction iscarried out by reacting appropriate amounts of reactants neat at roomtemperature and at autogenous pressure.

Imidization may be performed either chemically or thermally. Methods ofimidization are well known in the art and will not be described hereinin any great detail. The thermal imidization can be conducted by addingacetic anhydride and toluene and removing reaction solvent/toluene bydistillation. The distillation addition cycle can be carried out for 2-4hours during which time the solid content of reaction is maintained atan appropriate level, as for example at 10-15 percent.

The chemical imidization can be carried out by use of a mixture of equalmolar ratio of acetic anhydride and pyridine. The mixture of aceticanhydride and pyridine is poured into polyamic acid solution, and theimidization is allowed to proceed overnight at room temperature.

The modified phenolic resin of the invention depicted in Formula I usedas a precursor in the preparation of the resin of Formula II is preparedby a condensation polymerization reaction. In this reaction, an acylsubstituted aromatic compound of the formula: ##STR11## in which R₃, n,p, and q are as defined above, and U is a leaving group such as fluoro,chloro or bromo is reacted with phenolic of the formula: ##STR12##wherein R₃, --X--, q, r, o, p and n are as defined above preferablyunder nitrogen in an aprotic solvent and in the presence of an acidacceptor such as a tertiary amine as for example triethylamine.

Reaction temperatures can vary widely and are preferably from about 0°C. to about 120° C. with aqitation and more preferably from about 0° C.to about 30° C. Reaction pressures can vary videly. However, forconvenience, the reaction is carried out at autogenous pressure.

Useful aprotic solvents can vary widely, the only requirement being thatthe solvent is inert under the reaction conditions. Illustration ofaprotic solvents useful in the conduct of this reation are N,N-dimethylacetamide, N,N-dimethyl formamide, N-methyl-2 pyrrolidone, and dimethylsulfoxide. The preferred solvent is N-methyl 2-pyrrolidone.

Reaction times can vary considerably and will depend upon such factorsas the degree of agitation, temperature, nature and proportion ofreactants and the like. Preferred reaction times are from about 4 hoursto about 6 hours.

The reaction product can be recovered by conventional means. Forexample, the crude polymeric product can be recovered by pouring thereaction mixture into water. The final polymer can be reprecipitated bystandard technique such as redissolving in N-methyl 1,2-pyrrolidone andreprecipitating from water. The product can then be dried in vacuum ovenfor 24 hr.

The acyl substituted aromatic compounds and the phenolic resins used inthe preparation of the modified phenolic resins of this invention areknown materials, which can be obtained commercially or prepared by knownprocedures. For example, phenolic resins can be conveniently prepared byreacting an aldehyde such as formaldehyde and a phenol such as phenol inthe presence of an acid or base catalyst, and acyl substituted aromaticcompounds can be prepared by reacting an appropriate trimellitic acidanhydride with a halogenating agent such as thionyl chloride.

The phenolic resin of this invention as depicted in Formula II can becrosslinked or cured to form various partially cured, incompletely curedand completely cured resins. One partially cured, incompletely cured orcompletely cured resin is prepared by treating the phenolic resin ofFormula II in which Y is hydrogen with a conventional crosslinking agentsuch as hexamethylene tetra amine, paraformaldehyde and resole. Suitablecrosslinking reaction parameters are described in more detail in U.S.Pat. Nos. 4,096,108; 4,219,452; 4,218,361 and 4,268,657; and G. L.Brode, "Phenolic Resins", in Encyclopedia of Chem. Tech., 3rd Ed., Vol.17, p. 384 (1982) which are incorporated herein by reference.

Another partially, incompletely and completely cured resin is formed bysubjecting the resin of Formula II in which Y is hydrogen and --CN topolycyclotimerization. By the term "polycyclotrimerization" is meantforming a cyanurate ring system by the polymeric condensation of threearomatic cyanate groups to form the crosslinked aromatic ring system ofthe formula: ##STR13## Methods for conducting the polycyclotrimerizationof cyanurate compounds are well known in the art and include annealingabove about 200° C. For example, such procedures are described in U.S.Pat. No. 4,157,360 and Kunstoffe, Bd., 58, pp. 827-832 (1968) by R.Kubens et al. and Dokl, and Akad Naak SSSR, Vol. 202, pp. 347-350 (1972)by V.V. Korshak et al., which are hereby incorporated by reference.

A reinforced and/or filled compositions comprising the completely cured,partially cured, and incompletely cured compositions of this invention,and the precured compositions of Formula I and II which may be used inthe preparation of such reinforced compositions are also part of theinvention disclosed herein. The completely cured, precured, partiallycured, and incompletely cured compositions as described, may containfillers for use in where the structural strength and integrity of astructure has to be maintained, and for other purposes known to those ofskill in the art. Any suitable filler known to those of skill in the artcan be used. Such fillers may be selected from a wide variety of organicand nonorganic materials such as polymers, minerals, metals, metaloxides, siliceous materials and metal salts. Illustrative of usefulfillers are fiber glass, steel, abestos fibers, aramide, boron andcarbon fibers, as well as plate like, fibrous and particulate forms ofalumina, bross powder, aluminum hydrates, iron oxide, feldspar, leadoxides, asbestos, talc, barytes, calcium carbonates, clay, carbon black,quartz, novaculite and other forms of silica, kaolinite, aluminumsilicate bentonite, garnet, mica, saponite, beidelite, calcium oxide,fused silica, calcium hydroxide, etc. Other useful fillers includethermoplastic polymer as for example polyesters, polyimides, polyamides,polysulfones, polyaramids, polyester carbonates, polyethers,polyethersulfones, polyethylene, polypropylene, polycarbonates,polyetherimides, polysulfides, polyacrylates, polyvinyls and the like.The foregoing recited fillers are illustrative only and are not meant tolimit the scope of the fillers that can be utilized in this invention.Methods for producing reinforced and/or filled compositions include meltblending, extrusion and molding processes, simple mixing and dispersionfor both materials in a suitable medium by methods known in the art.

The precured, completely cured, incompletely cured and partially-curedcompositions of this invention are useful in forming a wide variety ofindustrial products, including shaped articles, as produced by knownshaping processes. Precured compositions can be formed (i.e., shaped)into articles which can then be cured to form completely cured,incompletely cured and partially-cured articles. Shaped articlesproduced from the polymer composition include windscreens such aswindshields, structural parts, canopies, door windows wire housing andthe like. The shaping process can be any process known to one skilled inthe art, such as injection, blow or extrusion molding. Another use ofthe crosslinked polymer of the member is a binding agents in themanufacture of friction materials such as brake linings, clutch facingsand transmission bands, as for example those described in U.S. Pat. Nos.3,966,670, 4,268,657, or 4,281,361. Still other uses of the polymers ofthis invention are molding materials, composites for use in themanufacture of structural parts and the like.

The following specific examples are presented to more particularlyillustrate the invention and are not to be construed as limitationsthereon.

EXAMPLE 1

A 5 g quantity of RD-27 (a novalac resin) was dissolved in a mixture of50 ml N-methyl 2-pyrolidone and 10 ml of pyridine. The mixture wasstirred for 20 minutes, while 2.8 g of trimellitic acid anhydride wasdissolved in 25 ml of N-methyl 2-pyrrolidone and added slowly to theabove mixture. The reaction was continued with stirring under nitrogenfor 3 hours. Oxydianiline (2.6 g) was dissolved in N-methyl 2-pyrolidoneand added to the above mixture. A exotherm was noticed [25°-28° C.), Thereaction was continued for 21/2 hours. The imidization was conducted byadding 5 ml of acetic anhydride and removing N-methyl2-pyrolidone/toluene by distillation. The distillation addition cyclewas carried out for 2 hours during which time about 100 ml of N-methyl2-pyrolidone/toluene mixture was collected. The product was poured into300 ml of vigorously stirred water. The polymer that precipitated wasfiltered and poured into 300 ml of acetone to remove impurities. Thepolymer was dried under vacuum oven at 100° C. for 24 hour.

EXAMPLE 2

A poly p-xylene phenolic (3 g) was dissolved in a mixture of 25 mlN-methyl 2-pyrolidone and 10 ml of pyridine. Trimellitic acid anhydride(2.5 g) was dissolved in 15 ml of N-methyl 2-pyrolidone and added slowlyto the phenolic solution. As the addition was completed, the color ofthe solution change from dark to orange. The reaction was continued for3 hours. A Oxydianiline (2.3 g) was then dissolved in 15 ml of N-methyl2-pyrolidone and added to the above mixture. After the addition of theoxydianiline, the reaction was continued for 21/2 hours. The mixture waschemically imidized by the addition of 10 ml of acetic anhydride,allowed to sit overnight. The reaction mixture was poured into water,and the polymer that precipitated, was filtered and poured into 300 mlof acetone to remove impurities. The polymer was dried under vacuum ovenat 100° C. for 24 hours.

EXAMPLE 3

Five grams of Novalac of number average molecular weight-620 wasdissolved in 50 ml of N-methyl 2-pyrolidone and 10 ml of pyridine. Themixture was stirred for 1 hr while 2.8 g of trimellitic acid anhydridewas dissolved in 25 ml of trimellitic acid anhydride was dissolved in 25ml of N-methyl pyrrolidone and added slowly to the above mixture. Thereaction was continued with stirring under nitrogen for 3 hours.4,4'-Diamino-diphenylmethane (MDA) (2.6 g) was added to the mixture andreaction was run for 31/2 hours. The mixture was chemically imidized byaddition of 10 ml of AC₂ O and imidization was continued overnight. Thereaction mixture was poured into water and filter. The light-yellowproduct was dired in vacuum overnight at 110° C.

EXAMPLE 4

Two grams of phenolic-polyester imide from Example 3 was dissolved in 15ml N-methyl 2 pyrolidone and few drops of triethylamine was added to themixture. Cyanogen bromide (1 g) was dissolved in 5 ml of NMP and addedto the phenolic solution. The reaction was continued for 2 hours. Theproduct was then isolated by precipitating in water. A light-yellowproduct resulted. The polymer was dried under vacuum over night at 100°C. for 24 hours.

EXAMPLE 5

A series of experiments were carried out for the purpose of evaluatingthe thermal characteristics of certain embodiments of this invention andto compare same to the base phenolic resin. In these experiments,thermogravimetric analysis (TGA) was carried out in an argon atmosphereto determine the weight loss of a sample as a function of temperatureand the % Char at 900° C. These experiments were carried out using aDupont-1090 thermogravimeter at a heating rate of 10° C./min. Thetypical sample size was 30-34 mg. The results of these experiments weset forth in the following Table I.

                                      TABLE 1                                     __________________________________________________________________________    Thermal Characterization of Phenolic-Polyesterimide System                             % Weight Loss at °C.                                                                     % Residue                                                                           Differential Scanning                        Sample   100                                                                              200                                                                              300                                                                              400                                                                              450                                                                              500                                                                              at 900° C.                                                                   Colorimetry Tg °C.                    __________________________________________________________________________    RD-27 (Novolac)                                                                          0.2                                                                            0.6                                                                              4.1                                                                              26.4                                                                             34.6                                                                             38.6                                                                               44.8                                                                              60                                           Ex. 1.   0  0  2.2                                                                              8.0                                                                              14.2                                                                             26.4                                                                             52    104                                          Ex. 2.   0  1.1                                                                              3.1                                                                              8.0                                                                              11.3                                                                             17 49    --                                           Poly p-xylene                                                                          0  7.2                                                                              14.6                                                                             18 23.8                                                                             30.8                                                                             36    23                                           phenolic (xylok)                                                              Ex. 3.   0  0  0  2.0                                                                               3.0                                                                             11.0                                                                             50    --                                           __________________________________________________________________________

What is claimed is:
 1. A modified phenolic resin of the formula:##STR14## --Z₁ -- and --Z₂ -- are the same or different and are divalentmoieties of the formula: ##STR15## o and p are the same or different ateach occurrence and are whole numbers from 0 to 4 with the proviso thatthe sum of o and p at each occurrence is equal to 4;q and r are the sameor different and are whole numbers from 0 to 3 with the proviso that thesum of q and r at each occurrence is equal to 3; Y is hydrogen, orhydrogen and --CN; --X-- and --R-- are the same or different at eachoccurrence and are a divalent organic radicals; R₃ is the same ordifferent at each occurrence and is a substituent other than hydrogenwhich is unreactive with amine functions; k is a positive whole number;and n is a positive whole number.
 2. A resin according to claim 1wherein Y is hydrogen.
 3. A resin according to claim 1 wherein fromabout 5 to about 80 mole percent of Y is --CN and the remainder ishydrogen.
 4. A resin according to claim 3 wherein from about 15 to about75 mole percent of Y is --CN.
 5. A resin according to claim 4 whereinfrom about 25 to about 50 mole percent of Y is --CN.
 6. A resinaccording to claim 5 wherein from about 30 to about 45 mole percent of Yis --CN.
 7. A resin according to claim 1 wherein:o and p are the same ordifferent and are numbers from 1 to 3 with the proviso that the sum of oand p is
 3. 8. A resin according to claim 7 wherein:o is 0 to 1; and pis 1 to
 3. 9. A resin according to claim 8 wherein:p is 3; and o is 0.10. A resin according to claim 1 wherein X is substituted orunsubstituted methylene or 1,4-phenyldimethylene, wherein permissiblesubstituents are alkyl having from 1 to about 10 carbon atoms, halogenand furyl.
 11. A resin according to claim 10 wherein X is a moiety ofthe formula: ##STR16##
 12. A resin according the claim 1 wherein n isfrom about 1 to about
 10. 13. A resin according to claim 12 wherein n isfrom 27 to about
 4. 14. A resin according to claim 1 wherein:q and r arethe same or different and are positive numbers from 0 to 3, with theproviso that the sum of q and r is
 3. 15. A resin according to claim 14wherein:r is 0 or 1; and q is 1 to
 3. 16. A resin according to claim 15wherein: o is 0; and p is
 3. 17. A resin according to claim 1 wherein R₃is alkyl.
 18. A resin according to claim 17 wherein R₃ is methyl orethyl.
 19. A resin according to claim 1 wherein --R-- is a divalentorganic radical selected from the group consisting of divalent aromaticradicals having from 6 to about 20 carbon atoms, alkylene having from 1to about 20 carbon atoms, cycloalkylene having from 3 to about 20 carbonatoms, polydiorganosiloxanes terminated with alkylene having from about2 to about 8 carbon atoms, and divalent radicals of the formula:##STR17## wherein Q is selected from the group consisting of: ##STR18##where y is from 1 to about
 20. 20. A resin according to claim 19 wherein--R-- is a divalent radical selected from the group consisting ofdivalent aromatic radical and divalent radicals of the formula:##STR19##
 21. A resin according to claim 20 wherein --R-- is selectedfrom the group consisting of phenylene, diphenylene, naphthalene anddivalent radicals of the formula: ##STR20## where Q is selected from thegroup consisting of ##STR21## where x is from 1 to about
 10. 22. Acomposition which comprises a modified phenolic resin according to claim1 and one or more fibrous or particulate fillers.
 23. A cured resinformed by curing the modified resin of claim 2 by treatment with achemical curing agent.
 24. A partially cured resin according to claim23.
 25. A completely cured resin according to claim
 23. 26. Anincompletely cured resin according to claim
 23. 27. A cured resin formedby heating the resin of claim
 3. 28. A completely cured resin accordingto claim
 27. 29. A partially cured resin according to claim
 27. 30. Anincompletely cured resin according to claim 27.